caffeine

noun

caf·​feine ka-ˈfēn 

ˈka-ˌfēn

: a bitter alkaloid C₈H₁₀N₄O₂ found especially in coffee, tea, cacao, and kola nuts and used medicinally as a stimulant and diuretic

Examples of caffeine in a Sentence

Her doctor told her to avoid caffeine.

Recent Examples on the Web

Stimulants such as caffeine are often considered the most effective ingredients in thermogenic fat burners like PrimeShred and Instant Knockout Cut. —Robert James and, Miami Herald, 8 Apr. 2024

Jitters and anxiety are usually limited to caffeine: Lots of fat burners contain caffeine in high doses, so check the dose aligns with your tolerance before taking. —Discover Magazine, 3 Apr. 2024

Certainly, a drink stuffed with huge amounts of caffeine will be energizing. —Yasmin Tayag, The Atlantic, 28 Mar. 2024

Caffeine Control: Limit caffeine consumption to before 12 p.m. for better sleep quality. —Maryal Miller Carter, USA TODAY, 25 Mar. 2024

The most dangerous ingredients in chocolate are caffeine and theobromine, which affect the nervous system and heart, cause dehydration and could even lead the dog to develop gastrointestinal distress, Cohen said. —Katie Wiseman, The Indianapolis Star, 28 Mar. 2024

To avoid getting the jitters or experiencing that dreadful caffeine crash, stick to no more than four cups a day. —Maria Berentzen, Vogue, 25 Mar. 2024

The combination of caffeine and l-theanine in chai can help with overall alertness, Crumble Smith says. —Clare Mulroy, USA TODAY, 18 Mar. 2024

Three types of natural caffeine boost circulation, rosehip oil nourishes, vitamin E fights free radicals (which are the culprit behind wrinkles), vitamin C peps up collagen, aloe hydrates, and rose hydrosol reduces inflammation. —Jamie Allison Sanders, Peoplemag, 12 Mar. 2024

Word History

Etymology

German Kaffein, from Kaffee coffee, from French café

First Known Use

circa 1823, in the meaning defined above

Phrases Containing caffeine

• caffeine-free

Kids Definition

caffeine

noun

caf·​feine ka-ˈfēn 

ˈka-ˌfēn

: a bitter stimulating compound found especially in coffee, tea, cacao, and kola nuts

Medical Definition

caffeine

noun

caf·​feine ka-ˈfēn, ˈka-ˌ; ˈkaf-ē-ən 

: a bitter alkaloid C₈H₁₀N₄O₂ found especially in coffee, tea, and kola nuts and used medicinally as a stimulant and diuretic

caffeinic

ka-ˈfē-nik  ˌkaf-ē-ˈin-ik 

adjective